We propose to use SAXS to study the self-association of the prion proteins. Structural transformation of these proteins is believed to be at the basis of a range of transmissible neurodegenerative prion diseases, of which examples include Creutzfeld Jacob Disease (CJD) in humans, Scrapie in sheep and Bovine Spongiform Encephalopathy (BSE) - or "mad cow disease". Heat-induced isomerization of the alpha-helical conformation of a recombinant form of the prion protein, alpha-rPrP to a multimeric beta-sheet form will be studied using SAXS. By measuring a series of scattering profiles during the time course of the isomerization reaction, it will be possible to determine the polydispersity of the resulting multimeric form and see how this depends on solvent conditions and also on various mutations which can be generated in the recombinant rPrP.